Folks--be careful when workin gon the AC system. 'Freon' is very dangerous if it leaks onto skin or the eyes and can cause blindness by freezing the cornea almost instantly.

If you are not very familiar with the principles and practicalities of automotive refrigeration, leave the recharging to a pro. Its very easy to overcharge and blow hoses and vey expensive hard parts--or hurt oneself badly.

If someone doesn't know what the service valves look like and where they are on their car--its probably not a good idea to suggest they add refrigerant.